Study: Drinking Coffee May Lower Cancer Risk in Women

Java junkies have another reason to love their morning cup: researchers say that drinking coffee is associated with a lower risk of endometrial cancer among women.

After looking at cancer rates among more than 67,000 women, aged 34 to 59, enrolled in the Nurses’ Health Study, senior author Edward Giovannucci of the Harvard School of Public Health and his team report that women who drank four or more cups of coffee a day over 26 years had a 25% lower risk of endometrial cancer, compared with those consuming less than a cup a day. Women who drank two or three cups a day had a 7% lower risk.

The benefit wasn’t a complete surprise, since coffee has been shown to lower estrogen and insulin levels, and higher levels of these hormones have been associated with an increased risk of endometrial cancer. But the new findings do help to clarify how obesity, estrogen and coffee might interact in triggering tumors.

In the study, obese women were more likely than lean women to show a coffee-associated drop in endometrial cancer risk. That may be due to the fact that, particularly after menopause, most of the estrogen a woman’s body makes is in the fat cells — so coffee’s estrogen-lowering effects may be more dramatic among women with more fat and, thus, more estrogen.

Giovannucci and his team also explored whether it was the caffeine or other components in coffee that may be responsible for its cancer-fighting effect. They found a similar but less dramatic reduction in cancer rates among women who drank at least two cups of decaffeinated coffee a day, compared with those drinking less than a cup a month, which implies that other components in coffee might be protecting the endometrium. Coffee also contains powerful antioxidants that may protect cells from becoming cancerous.

“The effect of coffee on estrogen and insulin seem to be due to other components in coffee that aren’t related to caffeine,” says Giovannucci. “There does seem to be a benefit that could be achieved through decaffeinated coffee too.”

That’s an important message, since it doesn’t mean that every caffeinated product, such as sodas, would have the same anticancer effect. In fact, caffeinated soft drinks might actually increase women’s risk of endometrial cancer by boosting sugar intake and, therefore, insulin levels. “It would be the completely wrong message if people thought that if coffee is good, then they might get the same benefit from caffeinated soft drinks,” says Giovannucci.

Further, while the study does link coffee consumption with a lower cancer risk, it does not prove a direct cause between the two. “It’s premature to recommend that women take up coffee to reduce their risk of endometrial cancer,” Giovannucci says.

It’s also important to note that the reduction in cancer risk associated with coffee doesn’t match that linked with losing excess weight — obesity remains a much greater risk factor for endometrial cancer than not drinking coffee.